Some challenges run better as a sequence of phases rather than one open submission window — for example an ideation phase followed by a prototyping phase, where only a shortlist advances. You can set this up from the Timeline tab in the creation wizard or from Manage → Phases on an existing challenge.
Each phase has its own start and end date, and the challenge tracks a "current phase" as it progresses. Participants only see the current phase's requirements, which keeps a multi-stage challenge from feeling overwhelming to someone just joining.
